/*
 * ElementListParameter.java July 2009
 *
 * Copyright (C) 2009, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.core;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;

import wx.xml.simpleframework.xml.ElementList;
import wx.xml.simpleframework.xml.stream.Format;

/**
 * The <code>ElementListParameter</code> represents a constructor
 * parameter. It contains the XML annotation used on the parameter
 * as well as the name of the parameter and its position index.
 * A parameter is used to validate against the annotated methods
 * and fields and also to determine the deserialized values that
 * should be injected in to the constructor to instantiate it.
 *
 * @author Niall Gallagher
 */
class ElementListParameter extends TemplateParameter {

    /**
     * This is the expression used to represent this parameter.
     */
    private final Expression expression;

    /**
     * This is the contact used to determine the parameter name.
     */
    private final Contact contact;

    /**
     * This is the label that will create the parameter name.
     */
    private final Label label;

    /**
     * This is the fully qualified path used for this parameter.
     */
    private final String path;

    /**
     * This is the actual name that has been determined.
     */
    private final String name;

    /**
     * This is the type of the label represented by this.
     */
    private final Class type;

    /**
     * This is the key that uniquely identifies this parameter.
     */
    private final Object key;

    /**
     * This is the index that the parameter was declared at.
     */
    private final int index;

    /**
     * Constructor for the <code>ElementListParameter</code> object.
     * This is used to create a parameter that can be used to
     * determine a consistent name using the provided XML annotation.
     *
     * @param factory this is the constructor the parameter is in
     * @param value   this is the annotation used for the parameter
     * @param format  this is the format used to style this parameter
     * @param index   this is the index the parameter appears at
     */
    public ElementListParameter(Constructor factory, ElementList value, Format format, int index) throws Exception {
        this.contact = new Contact(value, factory, index);
        this.label = new ElementListLabel(contact, value, format);
        this.expression = label.getExpression();
        this.path = label.getPath();
        this.type = label.getType();
        this.name = label.getName();
        this.key = label.getKey();
        this.index = index;
    }

    /**
     * This is the key used to represent the parameter. The key is
     * used to store the parameter in hash containers. Unlike the
     * path is not necessarily the path for the parameter.
     *
     * @return this is the key used to represent the parameter
     */
    public Object getKey() {
        return key;
    }

    /**
     * This is used to acquire the path of the element or attribute
     * represented by this parameter. The path is determined by
     * acquiring the XPath expression and appending the name of the
     * label to form a fully qualified path.
     *
     * @return returns the path that is used for this parameter
     */
    public String getPath() {
        return path;
    }

    /**
     * This is used to acquire the name of the parameter that this
     * represents. The name is determined using annotation and
     * the name attribute of that annotation, if one is provided.
     *
     * @return this returns the name of the annotated parameter
     */
    public String getName() {
        return name;
    }

    /**
     * This method is used to return an XPath expression that is
     * used to represent the position of this parameter. If there is
     * no XPath expression associated with this then an empty path
     * is returned. This will never return a null expression.
     *
     * @return the XPath expression identifying the location
     */
    public Expression getExpression() {
        return expression;
    }

    /**
     * This is used to acquire the annotated type class. The class
     * is the type that is to be deserialized from the XML. This
     * is used to validate against annotated fields and methods.
     *
     * @return this returns the type used for the parameter
     */
    public Class getType() {
        return type;
    }

    /**
     * This is used to acquire the annotation that is used for the
     * parameter. The annotation provided will be an XML annotation
     * such as the <code>Element</code> or <code>Attribute</code>
     * annotation.
     *
     * @return this returns the annotation used on the parameter
     */
    public Annotation getAnnotation() {
        return contact.getAnnotation();
    }

    /**
     * This returns the index position of the parameter in the
     * constructor. This is used to determine the order of values
     * that are to be injected in to the constructor.
     *
     * @return this returns the index for the parameter
     */
    @Override
    public int getIndex() {
        return index;
    }

    /**
     * This is used to determine if the parameter is required. If
     * an attribute is not required then it can be null. Which
     * means that we can inject a null value. Also, this means we
     * can match constructors in a more flexible manner.
     *
     * @return this returns true if the parameter is required
     */
    public boolean isRequired() {
        return label.isRequired();
    }

    /**
     * This is used to determine if the parameter is primitive. A
     * primitive parameter must not be null. As there is no way to
     * provide the value to the constructor. A default value is
     * not a good solution as it affects the constructor score.
     *
     * @return this returns true if the parameter is primitive
     */
    public boolean isPrimitive() {
        return type.isPrimitive();
    }

    /**
     * This is used to provide a textual representation of the
     * parameter. Providing a string describing the parameter is
     * useful for debugging and for exception messages.
     *
     * @return this returns the string representation for this
     */
    public String toString() {
        return contact.toString();
    }

    /**
     * The <code>Contact</code> represents a contact object that is
     * to be used for a label in order to extract a parameter name.
     * The parameter name is taken from the XML annotation.
     */
    private static class Contact extends ParameterContact<ElementList> {

        /**
         * Constructor for the <code>Contact</code> object. This is
         * used to create an object that acts like an adapter so that
         * the label can create a consistent name for the parameter.
         *
         * @param label   this is the annotation for the parameter
         * @param factory this is the constructor the parameter is in
         * @param index   this is the index for the parameter
         */
        public Contact(ElementList label, Constructor factory, int index) {
            super(label, factory, index);
        }

        /**
         * This returns the name of the parameter as taken from the XML
         * annotation. The name provided here is taken by the label
         * and used to compose a name consistent with how fields and
         * methods are named by the system.
         *
         * @return this returns the name of the annotated parameter
         */
        public String getName() {
            return label.name();
        }
    }
}